Lay and Lie

This is the crown jewel of all grammatical errors.
               “Lay” is a transitive verb. It requires a direct subject and one or more objects. Its present tense is “lay” (e.g., I lay the pencil on the table) and its past tense is “laid” (e.g., Yesterday I laid the pencil on the table). 
                “Lie” is an intransitive verb. It needs no object. Its present tense is “lie” (e.g., The Andes mountains lie between Chile and Argentina) and its past tense is “lay” (e.g., The man lay waiting for an ambulance). 
       The most common mistake occurs when the writer uses the past tense of the transitive “lay” (e.g., I laid on the bed) when he/she actually means the intransitive past tense of “lie" (e.g., I lay on the bed).